diff --git a/mlir/include/mlir/Dialect/StandardOps/IR/Ops.td b/mlir/include/mlir/Dialect/StandardOps/IR/Ops.td
--- a/mlir/include/mlir/Dialect/StandardOps/IR/Ops.td
+++ b/mlir/include/mlir/Dialect/StandardOps/IR/Ops.td
@@ -42,7 +42,8 @@
 // Base class for standard cast operations. Requires single operand and result,
 // but does not constrain them to specific types.
 class CastOp<string mnemonic, list<OpTrait> traits = []> :
-    Std_Op<mnemonic, !listconcat(traits, [NoSideEffect])> {
+    Std_Op<mnemonic,
+           !listconcat(traits, [NoSideEffect, SameOperandsAndResultShape])> {
 
   let results = (outs AnyType);
 
diff --git a/mlir/test/IR/invalid-ops.mlir b/mlir/test/IR/invalid-ops.mlir
--- a/mlir/test/IR/invalid-ops.mlir
+++ b/mlir/test/IR/invalid-ops.mlir
@@ -685,7 +685,7 @@
 // -----
 
 func @fpext_vec(%arg0 : vector<2xf16>) {
-  // expected-error@+1 {{are cast incompatible}}
+  // expected-error@+1 {{requires the same shape for all operands and results}}
   %0 = fpext %arg0 : vector<2xf16> to vector<3xf32>
   return
 }
@@ -757,7 +757,7 @@
 // -----
 
 func @fptrunc_vec(%arg0 : vector<2xf16>) {
-  // expected-error@+1 {{are cast incompatible}}
+  // expected-error@+1 {{requires the same shape for all operands and results}}
   %0 = fptrunc %arg0 : vector<2xf16> to vector<3xf32>
   return
 }